A gunman who brought Brisbane's Queen Street Mall to a standstill has spent the past decade in and out of prison and has a history of carrying weapons in public, a court has heard.

Queen Street Mall gunman Lee Matthew Hillier sentencing

A gunman who brought Brisbane's Queen Street Mall to a standstill has spent the past decade in and out of prison and has a history of carrying weapons in public, a court has heard.

Lee Matthew Hillier, 35, is being sentenced in the Brisbane District Court over last year's siege that sent the city's central pedestrian mall and surrounding buildings into lockdown.

Workers and shoppers fled Queen Street on March 8 when the heavily tattooed Hillier produced a gun, at one point holding it to his throat.

The 90-minute stand-off ended when police shot him with a combination of lethal and non-lethal rounds.

It was later discovered his semiautomatic pistol was not loaded.

Hillier has remained in custody since the incident and on Thursday Crown Prosecutor Belinda Merrin said he should be sentenced to eight years' imprisonment.

The court heard he had an ongoing drug addiction and a "significant and serious" criminal history including violent behaviour, weapons and property offences.

Less than two months before the siege Hillier had blown his own fingers off with a handmade shotgun.

Ms Merrin said the courts had been indulgent towards Hillier, and his propensity for carrying weapons in public meant he was a serious danger to community safety.

"The impact of the defendant's actions was to terrify many people who were going about their everyday lives and he did so in a very heavily populated area of our capital city," she said.

"The city was laid siege to his parade of erratic and aggressive behaviour whilst armed with a firearm."

Hillier pleaded guilty to five counts of assaulting police while armed, possessing a weapon, going armed to cause fear, dangerous conduct with a weapon, discharging a weapon in public, and three counts of unauthorised possession of explosives.

Some charges related to the earlier incident when he blew his fingers off.

Hillier also pleaded guilty to a string of traffic offences and breaching bail twice.

Defence barrister Simon Hamlyn-Harris said his client had had no intention of harming anyone, had been in a state of severe distress, and had been seriously wounded in the incident.